YTaO<sub>4</sub>/Y₂Zr₂O₇ Dual-Phase Ceramics with Enhanced Vickers Hardness, Fracture Toughness and High Thermal Expansion Properties for Thermal Barrier Coating Applications
Rare-earth tantalates (RETaO<sub>4</sub>) are considered as a type of emerging thermal barrier coating materials applied to the hot components of gas turbines and aerospace engines due to their excellent thermal stability, high-temperature fracture toughness, corrosion resistance and ext...
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| description | Rare-earth tantalates (RETaO<sub>4</sub>) are considered as a type of emerging thermal barrier coating materials applied to the hot components of gas turbines and aerospace engines due to their excellent thermal stability, high-temperature fracture toughness, corrosion resistance and extremely low thermal conductivity. However, the relatively low hardness and thermal expansion coefficients may limit their service lifetime in a harsh engine environment. To address the current limitation of rare-earth tantalates and further optimize the mechanical and thermal properties, the defective fluorite-structured Y₂Zr₂O₇ (YZ) was introduced as a second phase into the YTaO<sub>4</sub> (YT) matrix to form YT<sub>1−x</sub>–YZ<sub>x</sub> (x = 0, 0.25, 0.5, 0.75, 1) composite ceramics in this work. The mechanical and thermal properties of YT<sub>1−x</sub>–YZ<sub>x</sub> composite ceramics are significantly improved compared to pure-phase YTaO<sub>4</sub> ceramics. The Vickers hardness of YT<sub>1−x</sub>–YZ<sub>x</sub> (x = 0.25, 0.5, 0.75) composite ceramics is 9.1~11.3 GPa, which are 2~2.5 times higher than that of YTaO<sub>4</sub> (4.5 GPa). Among them, YT<sub>0.75</sub>–YZ<sub>0.25</sub> exhibits a maximum fracture toughness (3.7 ± 0.5 MPa·m<sup>1/2</sup>), achieving a 23% improvement compared to YTaO<sub>4</sub> (3.0 ± 0.23 MPa·m<sup>1/2</sup>) and a 118% improvement compared to Y<sub>2</sub>Zr<sub>2</sub>O<sub>7</sub> (1.73 ± 0.28 MPa·m<sup>1/2</sup>). The enhancement is attributed to the combined effect of the intrinsic strengthening of the second phase, as well as the residual stress and grain refinement caused by the introduction of a second phase. Additionally, the thermal expansion coefficients of YT<sub>1−x</sub>–YZ<sub>x</sub> composite ceramics at 1673 K range from 10.3 × 10⁻⁶ K⁻<sup>1</sup> to 11.0 × 10⁻⁶ K⁻<sup>1</sup>, which is also higher than that of YTaO<sub>4</sub> (10.0 × 10<sup>−6</sup> K<sup>−1</sup>). Consequently, the superior mechanical and thermal properties indicate that YT–YZ composite ceramics possess promising application prospects for thermal barrier coatings. |
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| spelling | doaj-art-378492e6f3df43e399f348bb486f1a3f2025-08-20T01:49:01ZengMDPI AGMetals2075-47012025-03-0115330710.3390/met15030307YTaO<sub>4</sub>/Y₂Zr₂O₇ Dual-Phase Ceramics with Enhanced Vickers Hardness, Fracture Toughness and High Thermal Expansion Properties for Thermal Barrier Coating ApplicationsZiyang Ruan0Zifan Zhao1Jing Feng2Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093, ChinaFaculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093, ChinaFaculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093, ChinaRare-earth tantalates (RETaO<sub>4</sub>) are considered as a type of emerging thermal barrier coating materials applied to the hot components of gas turbines and aerospace engines due to their excellent thermal stability, high-temperature fracture toughness, corrosion resistance and extremely low thermal conductivity. However, the relatively low hardness and thermal expansion coefficients may limit their service lifetime in a harsh engine environment. To address the current limitation of rare-earth tantalates and further optimize the mechanical and thermal properties, the defective fluorite-structured Y₂Zr₂O₇ (YZ) was introduced as a second phase into the YTaO<sub>4</sub> (YT) matrix to form YT<sub>1−x</sub>–YZ<sub>x</sub> (x = 0, 0.25, 0.5, 0.75, 1) composite ceramics in this work. The mechanical and thermal properties of YT<sub>1−x</sub>–YZ<sub>x</sub> composite ceramics are significantly improved compared to pure-phase YTaO<sub>4</sub> ceramics. The Vickers hardness of YT<sub>1−x</sub>–YZ<sub>x</sub> (x = 0.25, 0.5, 0.75) composite ceramics is 9.1~11.3 GPa, which are 2~2.5 times higher than that of YTaO<sub>4</sub> (4.5 GPa). Among them, YT<sub>0.75</sub>–YZ<sub>0.25</sub> exhibits a maximum fracture toughness (3.7 ± 0.5 MPa·m<sup>1/2</sup>), achieving a 23% improvement compared to YTaO<sub>4</sub> (3.0 ± 0.23 MPa·m<sup>1/2</sup>) and a 118% improvement compared to Y<sub>2</sub>Zr<sub>2</sub>O<sub>7</sub> (1.73 ± 0.28 MPa·m<sup>1/2</sup>). The enhancement is attributed to the combined effect of the intrinsic strengthening of the second phase, as well as the residual stress and grain refinement caused by the introduction of a second phase. Additionally, the thermal expansion coefficients of YT<sub>1−x</sub>–YZ<sub>x</sub> composite ceramics at 1673 K range from 10.3 × 10⁻⁶ K⁻<sup>1</sup> to 11.0 × 10⁻⁶ K⁻<sup>1</sup>, which is also higher than that of YTaO<sub>4</sub> (10.0 × 10<sup>−6</sup> K<sup>−1</sup>). Consequently, the superior mechanical and thermal properties indicate that YT–YZ composite ceramics possess promising application prospects for thermal barrier coatings.https://www.mdpi.com/2075-4701/15/3/307thermal barrier coatingsrare-earth tantalatescomposite ceramicsstrengthening mechanismmechanical and thermal properties |
| spellingShingle | Ziyang Ruan Zifan Zhao Jing Feng YTaO<sub>4</sub>/Y₂Zr₂O₇ Dual-Phase Ceramics with Enhanced Vickers Hardness, Fracture Toughness and High Thermal Expansion Properties for Thermal Barrier Coating Applications Metals thermal barrier coatings rare-earth tantalates composite ceramics strengthening mechanism mechanical and thermal properties |
| title | YTaO<sub>4</sub>/Y₂Zr₂O₇ Dual-Phase Ceramics with Enhanced Vickers Hardness, Fracture Toughness and High Thermal Expansion Properties for Thermal Barrier Coating Applications |
| title_full | YTaO<sub>4</sub>/Y₂Zr₂O₇ Dual-Phase Ceramics with Enhanced Vickers Hardness, Fracture Toughness and High Thermal Expansion Properties for Thermal Barrier Coating Applications |
| title_fullStr | YTaO<sub>4</sub>/Y₂Zr₂O₇ Dual-Phase Ceramics with Enhanced Vickers Hardness, Fracture Toughness and High Thermal Expansion Properties for Thermal Barrier Coating Applications |
| title_full_unstemmed | YTaO<sub>4</sub>/Y₂Zr₂O₇ Dual-Phase Ceramics with Enhanced Vickers Hardness, Fracture Toughness and High Thermal Expansion Properties for Thermal Barrier Coating Applications |
| title_short | YTaO<sub>4</sub>/Y₂Zr₂O₇ Dual-Phase Ceramics with Enhanced Vickers Hardness, Fracture Toughness and High Thermal Expansion Properties for Thermal Barrier Coating Applications |
| title_sort | ytao sub 4 sub y₂zr₂o₇ dual phase ceramics with enhanced vickers hardness fracture toughness and high thermal expansion properties for thermal barrier coating applications |
| topic | thermal barrier coatings rare-earth tantalates composite ceramics strengthening mechanism mechanical and thermal properties |
| url | https://www.mdpi.com/2075-4701/15/3/307 |
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